1. Field of the Invention
The present invention is directed to a surface mountable miniature incandescent lamp assembly, and more particularly to a surface mountable miniature incandescent lamp assembly which directs light predominantly in a one direction, and which is rotationally keyed for surface mounting so as to position the lamp for directing the light in the desired direction.
2. Brief Description of the Prior Art
Miniature incandescent lamps have many applications in electronic and like appliances and equipment, with digital watches serving as primary examples. It is generally recognized in the art that for economy of manufacture the miniature incandescent lamps must be adapted for surface mount technology, that is the miniature incandescent lamps must be capable of being incorporated in equipment (such as an electronic watch) in an electronic assembly line without the need of soldering or welding connections to a circuit board.
A miniature incandescent lamp assembly which is advantageously mounted to a circuit board without the need for soldering or welding connections to the circuit board, and which has other advantages, such as relative simplicity of manufacture and ease of assembly, is described in the present inventor's U.S. Pat. No. 5,138,226, assigned to the same assignee as the present application. U.S. Pat. Nos. 3,060,344, 3,346,751, 4,537,323, 4,713,580, 4,952,838, and 4,970,428 comprise more remote background to the present invention.
Because miniature incandescent lamps tend to be powered by relatively small power sources, such as the batteries of a digital watch, the power consumption of such lamps is an important factor in their design and use. In this regard it is well known that frequent use of the lamp of an ordinary digital watch significantly shortens the useful life of the battery, so much so that one minute of the activation of the incandescent lamp may reduce battery life for normal powering of the watch by several days. In light of this, it is desirable to reduce the power consumption of miniature incandescent lamps, and/or to utilize the light generated by the miniature lamp in a more efficient manner, so as to permit use of a lamp which draws less power from the battery. The present invention accomplishes these objectives while retaining the advantages of relative ease of manufacture and assembly of the miniature incandescent lamp described in U.S. Pat. No. 5,138,226.